Automatic device for regulating fuel injection in an internal combustion engine



Dec. 13, 1938. s. SUGIHARA 2,139,981

AUTOMATIC DEVICE FOR REGULATING FUEL INJECTICN IN AN INTERNAL COMBUSTION ENGINE Filed Dec. 16, 1936 Fig.1

Patented Dec. 13, 1938 UNITED STATES AUTOMATIC DEVICE FOR REGULATING FUEL INJECTION IN AN INTERNAL BUSTION ENGINE COM- Slmichi Sugihara, Toda-Machl, Naka-ku, Na-

goya, Japan, as'slgnor to Mitsubishi Jukogyo Kabushiki Kaisha, Tokyo, Japan Application December 16, 1936, Serial No. 118,232

In Japan January 23, 1

1 Claim.

This invention relates to an automatic device for regulating the amount of fuel supply from the fuel injection pump of an internal combustion engine responsive to variation of the pressure of the charging air.

In an internal combustion engine of the type in which volatile fuel such as gasoline is injected into the engine cylinder or into the suction pipe and is ignited by an electric spark, it is old to provide a bellows which functions responsive to the pressure variation in the suction pipe, and a servo-piston controlled by said bellows for automatically actuating a fuel injection regulating mechanism.

Further, it is also known that when carrying the device as above into practice, a proper ratio of fuel to air responsive to the output of the engine is obtained by employing a number of.

fuel-air ratio required by the engine takes a.

sudden change beyond certain output. For instance, in an aircraft engine, whilst it is desirable to maintain the fuel-air ratio as low as possible when the output is not so high, for instance when cruising, so as to attain economical fuel consumption, it is necessary to make the fuel-air ratio considerably higher in order to prevent overheating of the engine cylinders, exhaust valves, etc., when a higher output is tem porarily required as when taking-off or climbing, although the fuel consumption increases thereby.

In hitherto known devices, however, the length of the bellows varies as the output of the engine and it lengthens or shortens in a wide range, so that durability of the bellows is impaired. As a rule, bellows are of little strength and easily broken so that when it is subjected to expansion or contraction in a wide range in use, the life is greatly shortened. This is the reason why their length is preferably kept as nearly constant as possible.

The present invention meets with the above requirement in that the bellows make a/very small elongation or shrinkage only at a. midway of change of pressure of the suction pipe and when the pressure of thesuction pipe becomes a certain value, the bellows recover its original length so that this length is kept nearly constant with either a greater output or in a smaller output of the engine.

In the accompanying drawing, Figure 1 shows one form of the device according .to this invention by way of example.

Figure 2 shows diagrammatically a joint having a pair of two different springs employed in this device, and a diagram illustrating the operation of the invention.

Referring to the drawing, particularly Figure 1, I designates an engine cylinder; 2 a suction valve; and 3 a fuel injection valve. 4 is an ignition plug, and 5 is a suction pipe. The pressure in said suction pipe is led through a conduit 6 into a chamber 1, in which is provided a bellows 8 which is maintained nearly at vacuum. When the pressure in the suction pipe 5 increases, said bellows 8 is slightly contracted. As the righthand end of the bellows 8 is secured to the wall of the chamber 1, a pressure-oil distributing valve Ill secured to the left-hand end of said bellows moves to the right, compressing small spring l3 and large spring I in a box-like joint I2 by a disc I I which is fixed to the lefthand end of the distributing valve III. Therefore, the pressureoil introduced in the direction of arrow l5 passes through a space It in the distributing valve and an oil conduit l1 into the righthand space in a pressure-oil cylinder 18 containing a. servopiston l9, so that the latter is moved leftwards. The 'oil' in the lefthand space in the cylinder 18 is discharged through an oil conduit 20, a

space 2 l in the distributing valve, and an 011 'conduit 22 in thedirection of arrow 23. As the servo-piston l9 moves leftwards, a lever" 24 is oscillated about a pivot 25 in the direction of arrow 28, thereby shifting to the right a fuel supply regulating rod 28 of a fuel injection pump 21 for increasing the amount of fuel injection, at the same time also moving the joint-box I2 leftwards, so that the springs i3 and I4 are further compressed and tend to return the distributing valve In to the left. When the bellows 8 returns to its initial length, with the distributing valve closing the oil conduits l1 and 20, the servopiston i9 is stopped. When the pressure in the suction pipe 5 decreases, the bellows 8 slightly expands. moving the distributing valve I0 to the left, so that the disc il compresses another small spring 29 and large spring 30. The pressure-oil introduced in the direction of arrow l5 flows through the space [6 in the distributing valve and the oil conduit 20 into the space lefthand to the servo-piston i9, movingthe latter to the right, and the oil in the space right-hand to the servo-piston is discharged through the oil conduit 11 and a space 3| in the distributing valve in the direction of arrow 23. Upon rightward movement of the servo-piston I9, the fuel supply regulating rod 28 is moved to the left through the lever '24, decreasing thereby the amount of fuel injection. At the same time, the springs 29 and il in the joint-box II are further compressed, tending t return the distributing valve III to the right and, when the bellows 8 returns to its initial length, closing the oil conduits i1 and 20, the servo-piston II is stopped. Thus, it will be seen that the springs in the jointbox I! function responsive to the force exerted to the bellows 8 by the pressure in the suction pipe 5 and they produce the force justenough to return the pressure-oil distributing valve ID to its initial position closing the oil conduits l1 and 20, and that the servo-piston ll moves the lever 24 to the position in which said springs just produce the required amount of force,

Having substantially described the arrangement and operation of the device according to this invention, the operation of the springs in the joint-box it will now be described more in detail as follows:

In the embodiment shown inlFlgures 1 and 2, the box-like joint i2 contains two sets of spring device each consisting of two springs, one small and the other large. As shown in A in Figure 2, when the disc II on the lefthand end of the pressure-oil distributing valve lies in the centra position in tne joint I! and the tensions on the righthand and lefthand springs are just equal, the springs do not act upon the distributing valve at all. In the diagram P in Figure 2, point a along the line a--b until the disc Ii comes in contact with a spring support '32 as shown at B in Fig. 2. When the pressure in the suctionpipe further increases, the large spring I is compressed as shown at C in Fig. 2, so that the fuel injection is gradually increased along the line b-c in the diagram P. Now, when the pressure in the'suction pipe slightly decreases from that corresponding to the condition of A in Fig. 2, the

small spring 28 will be immediately compressed, so that the lever 24 of Figure 1 is oscillated in the direction reverse to the direction of arrow 28 according to the movement of the servo-piston l9, whereby the fuel injection rapidly decreases along the line a-d until the disc Ii comes in contact with another spring support 33 as shown at D in Figure 2. When the pressure in the suction pipe further decreases, the large spring ill is compressed as shown at E in Figure 2, so that so that the engine may be safely operated always maintaining good performance, without necessitating any special manipulation during operation.

What I claim is:

An automatic device for regulating fuel injection comprising a bellows adapted to expand and contract in response to pressure variations in the suction pipe of an internal combustion engine, a distributing valve, a, servo-piston controlled by said distributing valve for regulating the fuel supply from a fuel injection pump to the engine, a spring case, said distributing valve being disposed between said bellows and said spring case, said bellows being fixed at one end and, connected at its other end to one end of said distributing valve, a disc movable in said spring case and connected with the opposite end of said distributing valve, separate sets of springs located in said spring case, the springs of the respective sets being of different tension and acting against the opposite sides of said disc, and-means connecting said spring case with said servo-piston.

SHUICHI SUGIHARA. 

